719 FXUS61 KBOX 190155 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 955 PM EDT THU JUL 18 2013 .SYNOPSIS... HIGH PRESSURE OVER THE MIDWEST AND ATLANTIC COAST WILL BRING CONTINUED HOT AND HUMID WEATHER TO SOUTHERN NEW ENGLAND THROUGH SATURDAY. ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS EVENING AND FRIDAY. SATURDAY...AS A STRONG COLD FRONT APPROACHES FROM THE GREAT LAKES...THERE IS THE GREATER THREAT FOR STORMS. RELIEF FROM THE HEAT AND HUMIDITY WILL ARRIVE ON SUNDAY AND LAST THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... 945 PM UPDATE... LAST OF THE WEAKENING SHOWERS/TSTMS MOVING THROUGH NORTHERN HILLSBOROUGH COUNTY AND A BRIEF SHOWER IS POSSIBLE INTO ESSEX COUNTY MA THROUGH 11 PM. OTHERWISE LOOKING AT MAINLY DRY CONDITIONS OVERNIGHT. CONTINUED WARM AND RATHER HUMID WITH LOWS IN THE UPPER 60S TO MID 70S. PATCHY FOG DEVELOPING. MINOR ADJUSTMENTS MADE TO T/TD/POPS TO REFLECT CURRENT CONDITIONS AND TRENDS. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... *** EXCESSIVE HEAT WITH NEAR RECORD HIGH TEMPERATURES *** AS MID LEVEL RIDGE BEGINS TO SLIDE SE OF NEW ENGLAND WAA INCREASES THROUGHOUT THE COLUMN YIELDING H7 TEMPS WARMING FROM +9C TODAY TO +11C TOMORROW. THIS SHOULD STRENGTHEN THE MLVL CAP. ALL MODELS PICKING UP ON THIS WITH LITTLE IF ANY QPF BEING TRIGGERED FRI. THIS SEEMS REASONABLE GIVEN THE LACK OF ANY FORCING IN A CAPPED ENVIRONMENT. THEREFORE WILL LIMIT POPS TO AN ISOLATED AFTN/LATE DAY TSTM. REGARDING TEMPS...850 TEMPS WARM TO +20C/+21C TOMORROW. THIS COMBINED WITH GOOD MIXING VIA WSW BLYR WINDS WILL SUPPORT HIGHS FRI 95-100 AWAY FROM THE SOUTH COAST! SOME LOCATIONS WILL APPROACH RECORD HIGHS. SEE CLIMATE SECTION BELOW. THE ONLY GOOD NEWS IS THAT AN INCREASING WSW WIND WITH GUSTS UP TO 25-30 MPH WILL HELP TAKE THE EDGE OFF THE EXCESSIVE HEAT. HOWEVER THIS WILL BE MINIMAL GIVEN THE HIGH DEW PT AIRMASS. NEVERTHELESS WITH NEAR RECORD HIGHS OF 95-100 COMBINED WITH DEW PTS IN THE U60S AND L70S THERE IS A MODERATE TO HIGH PROBABILITY OF A FEW HOURS OF HEAT INDICES OF 105+ ACROSS THE GREATER BOSTON AREA NORTHWARD INTO THE MERRIMACK VALLEY OF SOUTHEAST NH. THUS AN EXCESSIVE HEAT WARNING HAS BEEN ISSUED FOR THIS AREA. ELSEWHERE A HEAT ADVISORY HAS BEEN POSTED FOR HEAT INDICES OF 100-104F. CLOSER TO THE COAST SW WINDS SHOULD KEEP HIGHS 85-90F WITH INDICES MU90S. THEREFORE WILL HOLD OFF ON ANY ADVISORIES FOR NOW. BEACH FORECAST...ANOTHER AWESOME BEACH DAY WITH HOT AND HUMID CONDITIONS. TEMPS 85-90 ALONG WITH A GUSTY SSW WIND OF 15-25 MPH WITH GUSTS TO 30 MPH POSSIBLE. THESE GUSTY WINDS WILL YIELD A BUILDING CHOPPY SURF AND A MODERATE RISK OF RIPS ALONG THE SOUTH COAST. OTHERWISE AN IDEAL BEACH DAY. FRI NIGHT... ANOTHER VERY WARM AND MUGGY NIGHT WITH LOWS 70-75 AND DEW PTS IN THE U60S TO L70S. THIS WILL LEAD TO ANOTHER ROUND OF PATCHY DENSE FOG. AN ISOLATED EARLY EVENING TSTM WILL DISSIPATE WITH SUNSET && .LONG TERM /SATURDAY THROUGH THURSDAY/... BIG PICTURE/PREFERENCES... MOSTLY A ZONAL FLOW BUT WITH A COUPLE OF SHORTWAVES MOVING THROUGH DURING NEXT WEEK. OVERALL...PREFER A BLEND OF GFS/ECMWF...AND USED A BLEND OF GMOS AND HPC GRIDS. THE DAILIES... SATURDAY... MANY FAVORABLE SIGNS FOR TSTMS. COLD FRONT IN THE ST LAWRENCE VALLEY WITH LEE TROUGH SETTING UP ACROSS NEW ENGLAND AND THE MID ATLANTIC COASTAL PLAIN. FULL SUN EXPECTED THROUGH MIDDAY WITH INCREASING CLOUDS AFTN. MIXING SHOULD REACH TO 800 MB WHERE TEMPS ARE 14-16C...THIS WOULD SUPPORT SFC MAX TEMPS 93F-97F BUT AFTERNOON CLOUDS MAY KEEP US A FEW DEGREES SHORT OF THIS. 90+ STILL LOOKS GOOD IN LOWER ELEVATIONS AWAY FROM THE COAST. THE 700 MB +10C RETREATS SOUTH DURING THE MORNING REMOVING THE LARGE SCALE CAP. UPPER TROUGH AXIS SWINGS THROUGH THE GREAT LAKES WITH JET OVER THE ST LAWRENCE VALLEY...AND THE RIGHT ENTRANCE REGION OF THE JET MOVING OVER SOUTHERN NEW ENGLAND. WINDS AT 850 MB ARE 25-30 KNOTS...WINDS AT 500 MB ARE 35-45 KNOTS WITH A CORE OF 50 KNOTS TO OUR WEST AND NORTH. SBCAPE IS FORECAST IN EXCESS OF 2000 J/KG. MID LEVEL LAPSE RATE IS AROUND 6.2C...COULD BE BETTER BUT ACCEPTABLE. PRECIPITABLE WATER VALUES WILL BE AROUND 2 INCHES. WE WILL MAINTAIN LIKELY POPS FROM SATURDAY AFTERNOON THROUGH EARLY SATURDAY NIGHT. LOCALLY HEAVY DOWNPOURS AND SOME ENHANCED WORDING. SUNDAY... COLD FRONT STARTS THE MORNING ALONG OR JUST SOUTH OF THE SOUTH COAST/ISLANDS. UPPER FLOW IS CLOSE TO PARALLEL WITH THE FRONT...BUT COULD BE ENOUGH CROSS FLOW TO NUDGE IT FARTHER SOUTH. UPPER JET WILL MOVE OFF THROUGH THE MARITIMES DURING THE DAY...BUT WE WILL REMAIN IN THE RIGHT ENTRANCE REGION MUCH OF THE DAY. SOME CONCERN WE COULD DESTABILIZE WITH DAYTIME HEATING...AND 850-800 MB MOISTURE LINGERS. BUT HIGH PRESSURE IS BUILDING IN WITH SUBSIDENCE AND MID LEVEL COLD ADVECTION IS RATHER SMALL. WILL EXPECT SOME DAYTIME CLOUD DEVELOPMENT BUT LITTLE PCPN OUTSIDE OF WIDELY SCATTERED SHOWERS SOUTH OF THE MASS PIKE. TEMPS AT 850 MB IN THE LOWER TEENS SO MAX TEMPS SHOULD BE IN THE LOW-MID 80S. MONDAY THROUGH THURSDAY... COLD FRONT REMAINS STALLED TO OUR SOUTH AROUND THE CHESAPEAKE BAY AREA. UPPER FLOW IS ROUGHLY ZONAL BUT WITH EMBEDDED SHORTWAVES. EITHER THE SHORTWAVE COULD GENERATE A FEW SHOWERS AS IT PASSES...OR IT COULD INDUCE A WAVE ON THE STALLED FRONT TO OUR SOUTH AND SPREAD SHOWERS NORTH TO OUR COAST. CURRENT MODEL TIMING WOULD BRING THESE SHORTWAVES THROUGH NEW ENGLAND TUESDAY AND POSSIBLY THURSDAY. BUT SHORTWAVE TIMING IN THE LONG RANGE PERIODS CAN AND WILL CHANGE. WE HAVE CHANCE OR SLIGHT CHANCE POPS THROUGH THE PERIOD WITH THE HIGHEST POPS ON TUESDAY AND THURSDAY. TEMPS ARE A BLEND OF HPCGRIDS AND GMOS...850 TEMPS AROUND 12C MONDAY RISING TO 15-16C LATER IN WEEK SUGGEST MAX SURFACE TEMPS UPPER 70S TO MID 80S. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. MODERATE CONFIDENCE THROUGH FRIDAY... TONIGHT... PATCHY MVFR STRATUS/FOG POSSIBLE ALONG THE SOUTH COAST AND INTERIOR VALLEYS. VFR ELSEWHERE. FRI... ANY PATCHY MVFR IN FOG WILL DISSIPATE BY 14Z YIELDING VFR CONDITIONS. GUSTY WSW WINDS DEVELOPING DURING THE AFTERNOON WITH GUSTS 25-30 KT LIKELY. LESS RISK OF TSTMS TOMORROW THAN TODAY WITH AREAL COVERAGE ISOLATED. FRI NIGHT... SW FLOW WILL LIMIT MVFR CONDITIONS IN FOG TO THE SOUTH COAST. VFR LKLY ELSEWHERE. SW WINDS REMAIN MODEST ACROSS CAPE COD AND THE ISLANDS BUT SHOULD SLACKEN INLAND. KBOS TERMINAL...MODERATE CONFIDENCE IN TAF TRENDS. SEA-BREEZE WELL ESTABLISHED ALREADY AND WILL MAKE ITS NATURAL SHIFT TO S TONIGHT THEN SW OVERNIGHT. SSW FLOW TONIGHT IS NOT VERY FAVORABLE FOR FOG AT BOS...AND SHOULD CONFINE MVFR STRATUS/FOG TO SOUTH COAST OF MA/RI. LESS RISK OF TSTMS FRI. KBDL TERMINAL...HIGH CONFIDENCE IN TAF. OUTLOOK...SATURDAY INTO TUESDAY... MODERATE CONFIDENCE. SATURDAY...A COLD FRONT WILL MOVE THROUGH NEW ENGLAND SATURDAY NIGHT. PLENTY OF SUPPORT FOR TSTMS TO DEVELOP DURING THE AFTERNOON, TSTMS WILL TAP A VERY HUMID AIRMASS...SO HEAVY DOWNPOURS ARE EXPECTED. ALSO STRONG WINDS ALOFT...SO STRONG POSSIBLY DAMAGING WIND GUSTS POSSIBLE AS WELL. MOST LIKELY TIME IS FROM MID AFTERNOON THROUGH EARLY NIGHT. WEST SOUTHWEST WINDS DURING THE DAY WITH NON- THUNDERSTORM GUSTS 20-25 MPH POSSIBLE...SHIFTING TO NORTH AFTER MIDNIGHT. VFR EXCEPT FOR BRIEF IFR POSSIBLE IN TSTMS AND IFR IN MORNING FOG. SUNDAY THROUGH TUESDAY... VFR WITH LIGHT EAST TO SOUTHEAST WIND. A FEW SHOWERS POSSIBLE TUESDAY. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. HIGH CONFIDENCE THROUGH FRIDAY NIGHT. TONIGHT... QUIET WEATHER WITH NOT MUCH WIND OR WAVE/SWELL. VSBY WILL LOWER LATER TONIGHT IN PATCHY DENSE FOG. FRI... INCREASING SW WINDS WITH GUSTS UP TO 25-30 KT...HIGHEST NEAR SHORE. TSTMS NOT EXPECTED. PATCHY DENSE FOG EARLY BURNS OFF BY MID MORNING. FRI NIGHT... MODEST SSW WINDS CONTINUE. WINDS VEER TO MORE WSW WHICH WILL LIKELY LIMIT FOG ESPECIALLY NEAR SHORE. THUS BETTER VSBY. OUTLOOK...SATURDAY INTO TUESDAY... SATURDAY AND SUNDAY... WEST TO SOUTHWEST WINDS MAY GUST TO 25 KNOTS SATURDAY ESPECIALLY NEAR CAPE COD. A COLD FRONT WILL SWING SOUTH ACROSS NEW ENGLAND SATURDAY...CROSSING THE WATERS SATURDAY NIGHT AND SUNDAY. SHOWERS AND THUNDERSTORMS ARE LIKELY WITH THIS FRONT. THUNDERSTORMS WILL PRODUCE HEAVY DOWNPOURS AND MAY CAUSE STRONG OR DAMAGING WIND GUSTS. WINDS BECOME EAST TO NORTHEAST AND DIMINISH ON SUNDAY. SEAS WILL BE 5 TO 7 FEET AHEAD OF THE FRONT...SUBSIDING AFTER THE COLD FRONT MOVES THROUGH. MONDAY AND TUESDAY... HIGH PRESSURE BUILDS OVER NORTHERN NEW ENGLAND BRINGING LIGHT EAST TO SOUTHEAST WINDS. LOW CONFIDENCE OF SHOWERS TUESDAY. && .CLIMATE... PRELIMINARY CLIMATE REPORT SHOWED SOME WARM MINIMUM TEMPS AT BOSTON-PROVIDENCE-WORCESTER. DEWPOINTS ARE LOW ENOUGH FOR TEMPS TO FALL BELOW THESE LEVELS OVERNIGHT...SO THE RACE WILL BE ON TONIGHT TO SEE HOW FAR TEMPS FALL BY 1 AM /MIDNIGHT LST/. RECORD HIGH MINIMUMS FOR TODAY 7/18 BOS...77/1969 PVD...75/1982 /LATEST YEAR/ BDL...77/1982 ORH...73/2006 /LATEST YEAR/ RECORD HIGHS FOR FRI 7/19... BOS...98/1982...FORECAST HIGH...99 PVD..100/1977...FORECAST HIGH...96 BDL..100/1991...FORECAST HIGH...99 ORH...95/1991...FORECAST HIGH...95 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...HEAT ADVISORY FROM 11 AM TO 7 PM EDT FRIDAY FOR CTZ002>004. AIR QUALITY ALERT FROM 11 AM TO 11 PM EDT FRIDAY FOR CTZ002>004. MA...HEAT ADVISORY FROM 11 AM TO 7 PM EDT FRIDAY FOR MAZ002>004- 008>012-017-018-026. AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR MAZ020>024. AIR QUALITY ALERT FROM 11 AM TO 11 PM EDT FRIDAY FOR MAZ005- 012>014-026. EXCESSIVE HEAT WARNING FROM 1 PM TO 7 PM EDT FRIDAY FOR MAZ005>007-013>016. NH...HEAT ADVISORY FROM 11 AM TO 7 PM EDT FRIDAY FOR NHZ011-015. EXCESSIVE HEAT WARNING FROM 1 PM TO 7 PM EDT FRIDAY FOR NHZ012. RI...HEAT ADVISORY FROM 11 AM TO 7 PM EDT FRIDAY FOR RIZ001>004. AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR RIZ003>008. AIR QUALITY ALERT FROM 11 AM TO 11 PM EDT FRIDAY FOR RIZ001>008. MARINE...SMALL CRAFT ADVISORY FROM 11 AM TO 8 PM EDT FRIDAY FOR ANZ230>237-251. && $$ SYNOPSIS...WTB/NOCERA NEAR TERM...KJC/NOCERA SHORT TERM...NOCERA LONG TERM...WTB AVIATION...WTB/NOCERA MARINE...WTB/NOCERA CLIMATE...